Sometimes, it is not clear who is responsible for claims being made on a website. Responsible websites will provide appropriate contact details, but occasionally the actual seller will not be obvious. However, there are easy steps you can take to find out who owns the domain name — although this could conceivably be different to the person or company responsible for the claims made on that website. Occasionally, some useful information can be gleaned from knowing who owns the domain name.
The domain name is what you type into a browser to take you to a website. This is usually very closely related to the organisation that runs the website and advertises its products or services.
The Whois system can provide the name of the domain name owner (the Registrant) and contact details. There are many websites that provide Whois services including Who.is and Network Tools. Some can provide other useful information as well.
As an example, lets see what information can be found for the website of the British Chiropractic Association, www.chiropractic-uk.co.uk.
Using Network Tools, type their domain name (chiropractic-uk.co.uk) into the box, ensure 'Whois' is selected and click on 'Go'.
Since we are checking a UK website, the results come from the UK Registry operator (Nominet):
Results returned from whois.nic.uk:
British Chiropractic Association
c/o Typeline, 26 The Hawthorns
This is publicly available information and gives us the name and address of the Registrant.
Note that if the domain is used as part of a business, trade or profession, Nominet Terms and Conditions require that the Registrant's name and address are made public and accessible to whois queries.
If you find a website that is clearly part of a business, trade or profession, but which has the Registrant type as 'UK Individual' you can report this to Nominet who will investigate and may take action against the Registrant.
This simple Whois query will usually give you details of who controls the website and therefore the person or company responsible for claims made on that website. This may also indicate a link with some other organisation.
However, even if you are not sure who owns the domain name or who runs the website, the onus is not on you as complainant to provide that information; you should still submit the complaint and leave it to that organisation to find out.